If Brent Grimes is as talented as I think he is, if he has recovered from an Achilles injury the way it seems he has, then the Miami Dolphins have the shut down cornerback they so badly need.

There were plenty of important offseason acquisitions for this team. Upgrades on both sides of the ball. But the signing of Grimes may very well go down as one the most significant moves. This is a player who earned a trip to the Pro Bowl in 2010, a player with unyielding confidence and a tenacity you even begin to notice during OTAs. There is a reason the Atlanta Falcons designated Grimes as their “franchise player” following the 2011 season.

Yes, this is a player who can clearly make a difference.

“I’m here to make plays,” he said. “That’s what I’m all about.”

When you look closer at Grimes, when you study the road he has taken to get here, the respect and admiration only increases. Undrafted out of tiny Shippensburg University. Signed with the Falcons in 2006 as the longest of long shots. Was shipped off to Germany in the old NFL Europe league. Lived the life of a practice squad player. Was cut a couple of times.

Very few people gave Brent Grimes much of a chance.

Except Brent Grimes.

“People always point to my height,” he said. “But it’s not like I’m 5-5 or something. The important thing isn’t how tall you are; it’s how you play.”

For the record, Grimes is listed at 5-10, but that could be a little generous. Do the Dolphins care? “He plays much bigger than his size,” said coach Joe Philbin.

It was only because of that Achilles injury suffered last September that Grimes became available to the Dolphins. There are always questions surrounding an injury of this kind. Would he regain his mobility? Would the injury linger? How would it affect him mentally?

The Falcons balked at offering Grimes a new contract. The Dolphins instead signed him to a one-year deal. Based on what I have seen so far, it is money well spent.

“I don’t like putting a percentage on it, but I’m getting healthier every day,” Grimes said. “It’s all about being ready when training camp starts.”

If what I saw during the OTAs isn’t the 100 percent version of Grimes, then I can’t wait to see what he looks like when he gets there. The first thing you notice is his instincts. There is no wasted motion. He anticipates, reacts and moves in an almost effortless manner.

“I like the way he plays,” said Philbin. “Always have.”

The Dolphins are in the midst of a shake-up at cornerback. Vontae Davis and Sean Smith are off to other teams. A second and third round pick were brought in to provide competition and depth. While the Dolphins won’t come out and say it, I believe they are counting on Grimes to man one of the starting spots, perhaps the guy that is lined up against the other team’s No. 1 receiver.

See, what attracted the Dolphins to Grimes and what sets him apart from so many other cornerbacks is his ability to do something special. He succeeds where the Dolphins struggled a season ago, making game-changing plays. He had six interceptions in 2009 and five in 2010. To put that in perspective, no Dolphins cornerback had more than two interceptions last season.

“There is nothing like intercepting a pass,” he said. “It’s the greatest feeling a cornerback can have. I know what’s expected of me. It’s all about forcing turnovers.”

Grimes pays so much attention to the football that he grips one during the stretching period, and won’t let go. Just like he won’t let go of all those doubters who questioned his ability. Sure, he would have preferred being drafted. No doubt, his dream wasn’t to play in Europe or languish on some practice squad waiting for his chance.

But today all of that serves as added motivation. He may be turning 30 in July but the way he looks at it, “I still have a lot to prove.”

He isn’t discouraged by signing just a one-year contract with the Dolphins nor is he putting added pressure on himself given the uncertainty of his future. It is all about the now for Brent Grimes. And what he sees in these Dolphins is a great opportunity to succeed, a chance to be with a team that is clearly on the rise and to play on a defense that covets his skills.

“I like it here,” he said. “The coaches, the players, the system it all seems to work for me.”

You watch Grimes on the practice field and quickly you lose sight of any height disadvantage. You see his relentless nature; how quickly he breaks on the ball and how No. 21 always seems to always be around the action. On one steamy day last week, he was lined up one-on-one against Mike Wallace, perhaps the fastest receiver in the league. Wallace gave him a quick move and then took off. But Grimes stayed with him step-for-step and the ball bounced harmlessly to the ground. A sore Achilles? Not on that play.

Grimes stood underneath the team’s practice bubble early Wednesday afternoon, talking about his career, his accomplishments and his new team. I asked him about the last time he took an interception to the house.

His eyes widened, his smile broadened.

“Been way too long,” he said. “I’m definitely due for one.”

It’s that type of attitude that made Brent Grimes so attractive to the Miami Dolphins.